class A{ 
   final double PI = 3.1415926;
   public double getArea(final double r){
      return PI*r*r;
   }
    public final void speak(){
       System.out.println("您好 , how's eveything here ?");
    }
}
public class Example5_9{
   public static void main (String args[]){ 
      A a =new A();
      System.out.println("面积 :"+a.getArea(100));
      a.speak();
   }
}
